Neoadjuvant Hormonal Therapy Combined With Chemoimmunotherapy

Inclusion Criteria: 1. Patients ≥ 18 years of age with histologically, and radiographically confirmed non-metastatic ER-positive (defined as ≥30% of positive cells) and HER2-positive (defined as overexpression by immunohistochemistry (3+) or 2+ and positive by defined by fluorescence or dual in situ hybridization.) breast cancer with minimal tumor size over 2 cm (≥T2 lesion) to receive neoadjuvant chemotherapy recommended by the treating physician 2. Eastern Cooperative Oncology Group (ECOG) performance status score \< 1 3. Absolute neutrophil count \> 1500 mm3, platelet count ≥ 100×109 L, hemoglobin ≥ 8.5 g/dL 4. Serum creatinine ≤1.5 times the upper limit of the normal range, total bilirubin ≤ 1.5 X ULN (≤ 3 mg/dL if clinically diagnosed with Gilbert syndrome) AST/ALT ≤ 2.5 X ULN (AST/ALT ≤ 5X ULN if clinically diagnosed with Gilbert syndrome) 5. Women of child-bearing potential (i.e., women who are pre-menoposaul or not surgically sterile) must have a negative serum pregnancy test within 2 weeks prior to beginning treatment Exclusion Criteria: 1. Uncontrolled cardiac disease, such as angina, hypertension or significant arrhythmias 2. LVEF (left ventricular ejection fraction) \< 50% on any prior assessment. Note: Assessment of LVEF is done before and after trastuzumab-based chemotherapy as standard of care 3. Pregnant or lactating females 4. Inability to complete informed consent process and adhere to the protocol treatment plan and follow-up requirements 5. Concurrent severe illness such as active infection, or psychiatric illness/social situations that would limit safety and compliance with study requirements